The present invention relates to a new and improved chemical attack polish and process for polishing metal surfaces. The chemical attack polish includes Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and water. The metal polishing procedure comprises saturating a polishing cloth with the chemical attack polish of the present invention, adding submicron particles of abrasive materials (e.g. alumina) to the cloth, and polishing the metal surface.
Various mechanical polishing techniques have been proposed in an attempt to achieve flat surfaces for nickel-base alloys and stainless steels, substantially free of microscratches and flowed metal. For example, mechanical polishing of nickel-base alloys or stainless steels has been performed with standard diamond and aluminum oxide abrasives using a vibratory polisher. This technique required abnormal polishing times of approximately two hours. The problems with these procedures are: (1) they are long and laborious; (2) they leave some microscopic scratches on the metal surfaces which often interfere with microscopic evaluation, and (3) they leave a layer of flowed metal of indetermined thickness which must be removed by etching to reach an undisturbed or true surface condition.
Recently, efforts have been directed to developing a chemical attack composition and polish procedure which avoids the disadvantages observed with the above described mechanical techniques. A successful chemical attack polish for Zirconium-base alloys has been developed at Knolls Atomic Power Laboratory. However, this attack polish applied to nickel-base alloys and stainless steels has not been effective. Accordingly, the problem of developing a suitable chemical attack polish and polishing procedure for nickel-base alloys and stainless steels has not been solved.